1. Field of the Invention
The present invention relates to a vibration isolator that can dampen payload movement in both vertical and horizontal directions.
2. Background Information
Vibration isolators are used to isolate and damp vibration loads on an adjoining structure that is commonly referred to as a payload. The payload may be a table that is part of a semiconductor wafer fabrication system. The payload may be subjected to shock/vibration loads in both a vertical direction and a horizontal direction. For this reason vibration isolators are designed to dampen energy applied in both the vertical and horizontal directions.
U.S. Pat. No. 3,784,146 issued to Matthews discloses a vibration isolator which contains a piston that is coupled to a support plate by a plurality of cables. The piston is located within an air cylinder that can dampen vertical shock/vibration loads applied by the payload.
The cables allow the support plate to move within an inner cavity of the piston. The piston inner cavity includes a damping fluid that dampens shock/vibration loads applied in the horizontal direction.
It has been found that the damping oil will sometimes leak, thereby requiring a repair or replacement of the vibration isolator. Leaking fluid may therefore reduce the effective life of the isolator. Additionally, having to seal and charge a vibration isolator with damping fluid increases the cost of mass producing the isolator.
One embodiment of the present invention includes a vibration isolator that has an elastomer, which couples a support plate to a piston. The piston can move within an inner chamber of an isolator housing.